Function addFileNameInError

source/MRMesh/MRStringConvert.h:103–108

/// if (v) contains an error, then appends given file name to that error
template<typename T>
[[nodiscard]] inline Expected<T> addFileNameInError( Expected<T> v, const std::filesystem::path & file )
{
    if ( !v.has_value() )
        v = unexpected( v.error() + ": " + utf8string( file ) );
    return v;
}

/// in case of empty vector, returns "Empty"
/// in case of single input file.ext, returns ".EXT"